If a dhcp server cannot be contacted the host uses

Info icon This preview shows pages 35–37. Sign up to view the full content.

View Full Document Right Arrow Icon
If a DHCP server cannot be contacted, the host uses APIPA to assign itself an IP address. The host only configures the IP address and mask. It does not assign itself the default gateway and DNS server addresses. For this reason, APIPA can only be used on a single subnet.
Image of page 35

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full Document Right Arrow Icon
You can use APIPA instead of a DHCP server, but it should only be used on a small network that does not need default gateway or DNS server settings configured. APIPA is the term used by Microsoft Windows. On other systems (e.g., Linux), this functionality is known as link-local addressing. Alternate IP configuration With an alternate IP configuration, the system attempts to use DHCP for TCP/IP configuration information. If a DHCP server cannot be contacted, the static configuration values are used. When you configure an alternate IP address, APIPA is no longer used. Use an alternate configuration: If you have a computer (e.g., a laptop) that connects to two networks (i.e., one with a DHCP server and another without a DHCP server). If you want to provide values to properly configure the computer in case the DHCP server is unavailable. You should know the following facts about IP address assignments: By default, all Windows computers try to use DHCP for TCP/IP configuration information. If your computer has used APIPA because the DHCP server is unavailable, it will have an IP address in the 169.254.x.x range. The workstation will be able to communicate with other hosts that have addresses in this range, but will not be able to communicate with hosts on other networks. When you configure a static IP address, you disable DHCP and APIPA. If you use a DHCP server for IP address configuration, you can still manually configure DNS server addresses. By default, a Windows workstation will use the hosts file to resolve hostnames into IP addresses first. If a match can't be found for the hostname to be resolved in the hosts file, the workstation will contact the DNS server it has been configured to use. IP Version 6 0:00-0:21 It may be hard to believe, but the Internet is out of IP addresses. The Internet Assigned Numbers Authority, or IANA, who is responsible for designated IP address to the Internet, have exhausted, essentially, all available IP, Version 4 addresses, which are the IP addresses you are familiar with. More Addresses Needed 0:22-1:39 This wasn't really a surprise for anyone. People in the industry knew this day was coming. They knew because IPv4 addresses are limited to just under 4.3 billion unique addresses. This may seem like a lot, but remember, some IPv4 addresses are reserved for experimental purposes. Other IPv4 address blocks are reserved for internal addresses. This leaves just a fraction of the addresses for Internet assignment.
Image of page 36
Image of page 37
This is the end of the preview. Sign up to access the rest of the document.

{[ snackBarMessage ]}

What students are saying

  • Left Quote Icon

    As a current student on this bumpy collegiate pathway, I stumbled upon Course Hero, where I can find study resources for nearly all my courses, get online help from tutors 24/7, and even share my old projects, papers, and lecture notes with other students.

    Student Picture

    Kiran Temple University Fox School of Business ‘17, Course Hero Intern

  • Left Quote Icon

    I cannot even describe how much Course Hero helped me this summer. It’s truly become something I can always rely on and help me. In the end, I was not only able to survive summer classes, but I was able to thrive thanks to Course Hero.

    Student Picture

    Dana University of Pennsylvania ‘17, Course Hero Intern

  • Left Quote Icon

    The ability to access any university’s resources through Course Hero proved invaluable in my case. I was behind on Tulane coursework and actually used UCLA’s materials to help me move forward and get everything together on time.

    Student Picture

    Jill Tulane University ‘16, Course Hero Intern